In general, a PCB is a circuit board on which electronic devices are mounted and components or signal lines are electrically connected to each other.
The circuit is made by pressing a copper foil on one or both sides of an insulation plate made of an insulation material such as a phenol resin, epoxy resin, etc. forming a conductive pattern on the copper foil, and removing some of the copper film by etching away unnecessary parts.
These circuit boards are classified into a normal circuit board, a carbon carbon circuit board, a metal circuit board, a multilayer circuit board, a Flexible circuit board, etc. according to structures.
In recent years, a problem occurs with a circuit board used with various components as well as LEDs that the circuit board has a low heat radiation effect. Therefore, metal circuit board adopting metal materials such as aluminum or copper alloys, etc. are developed and the metal circuit boards are widely and highly accepted in the market.
In particular, in relation to a demand for a metal circuit board for mounting LEDs, a demand for a metal circuit board for mounting LEDs on which structural formations such as bending, pressing, etc. can be applied rises in recent years.
An LED light module using a metal circuit board is illustrated in FIGS. 1 and 2 as an example of the metal circuit board for mounting LEDs.
In this LED light module, a plurality of aluminum plates 2 are arranged with a constant spacing between them on a rear surface of a metal flexible PCB 1 and the aluminum plates are fixed on the rear surface by a double-sided adhesive film.
And, an LED chip 3 is mounted on an upper surface position of the PCB corresponding to the aluminum plate 2 which is attached to the rear surface of the metal flexible PCB 1, which completes the PCB light module.
When this PCB light module is positioned on a stepwise injection molded product 4, a flexible portion is bent and the aluminum plate 2 is placed on a horizontal portion of the injection molded product 4, such that the PCB light module is placed in a stepwise shape. Therefore, the LED light can be emitted forward.
On the other hand, this conventional PCB light module has the following problems.
First, the conventional PCB light module does not have a structure made only of a metal circuit board, and the aluminum plate is arranged away from the rear surface of the flexible circuit board by a predetermined spacing, which results in a poor heat radiation effect. Therefore, high performance LED chips cannot be used for the PCB light module and this could degrade the brightness of the PCB light module with the LED chips.
Second, since the aluminum plate is attached to the rear surface of the flexible circuit board by a double-sided adhesive tape, a bubble can be generated during a surface mount technology (SMT) process at a temperature of about 300 degrees, which causes failures to occur in products.
Third, since the aluminum plate is attached to the flexible PCB, it takes long to attach the aluminum plate. Also, since the aluminum plate needs to be attached at an accurate position, high accuracy is required, and the high accuracy requirement could make the manufacturing processes complex and raise the manufacturing cost.